This invention relates to the production of silica-titania cogels.
Since its commercialization in the 1950's, chromium oxide on silica has become the dominant catalyst system used throughout the world to produce high density polyethylene. Over the years various refinements have been made in these catalysts, one of the most significant being the discovery that the presence of titanium imparts many beneficial characteristics to the catalyst. It has further been discovered that the very best results are generally obtained by coprecipitating an alkali metal silicate and a titanium compound to give a silica-titania cogel. While this represents an extraordinarily satisfactory product from the standpoint of catalyst properties, it is hard to make because of the necessity to wash out alkali metal ions and because of the necessity to use a volatile, water-miscible organic solvent to very carefully remove the water.